Drill bits having polycrystalline diamond cutters have reduced the cost of fabricating diamond bits. The cutters comprise diamond particles bonded to a support base member, and the support base member is fitted into the lowermost face of the drill bit, with the face of the diamond cutter being orientated respective to the bit face so that optimum penetration is achieved. During the drilling process, it is necessary to cool and clean the face of the bit, or otherwise the cutters will not properly perform; and furthermore, they will abraid away more rapidly unless adequate cooling and cleaning is provided to the bit.
During the drilling of a borehole with a diamond cutter drill bit, it is customary to circulate drilling fluid, such as drilling mud or air, down through the drill string and through an axial passageway formed within the drill bit. The passageway is connected to provide both drilling fluid at the face of the bit, thereby lubricating, cooling, and cleaning the bit; and at the same time, transfering or circulating the removed formation to the surface of the earth.
In order to achieve a suitable cleaning and cooling action for the bit, it is desirable to provide a plurality of outlets at the bit face in order to maintain each individual diamond cutter in proper operating condition. Therefore, the passageways leading to the outlets at the face of the bit are usually drilled at an angle respective to the longitudinal axial centerline of the bit body. This arrangement of the outlets result in drilling fluid exiting the bit such that the fluid is usually directed radially outwardly away from the bit face, which is not an optimum design expedient.
It would, therefore, be desirable to be able to provide the drilling fluid outlet at the face of the bit with a nozzle, and to be able to orient the nozzles in the most optimum direction respective to one another and to the diamond cutters. Such a desirable feature is the subject of the present invention.